Making Metal Roofing

The biggest advancement in metal roofing from 100 years ago has been the availability and technology associated with forming and processing equipment. There is an abundance of forming equipment used to make the result easier, more cost effective, advanced and weathertight. These fabrication advancements include rollforming, bending, seaming, slicing and shearing of the metal to make trims and roof accessories.

The process of metal forming has evolved and improved

By James Hazen

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Fifty years ago, the tools and processes involved in forming rolled sheet metal into metal shapes were quite different. Sheet metal workers were referred to as tin knockers and were considered experts in crafting metal shapes using a variety of hand tools and hammers. The distinct sound of banging on the metal was and continues to be heard on job sites and sheet metal shops today. With all the handwork, metal thicknesses were generally lighter and more malleable to allow for the techniques used in the trade.

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Today, options for copper, zinc, steel and aluminum panels are all becoming more widely used and accepted across the industry in a variety of colors, thicknesses and warranty options. For this article we’ll discuss some of the steps for fabricating a 2,000-square-feet Kynar painted Galvalume coil that is 24 inches wide into a small metal roofing system project.

Fabricating a Project

To begin, a coil of metal is loaded onto a de-coiler using a forklift and some rigging equipment. Most often a forklift is used for material handling as coils can weigh in excess of 2,000 pounds. Overhead hoists and other rigging equipment can also be used in both factory and field settings. The de-coiler holds the coil and allows metal to be pulled/rolled off it. In this case, sheets are being cut off into 10-foot sections to make flashings and accessory package. While shorter or longer lengths may be desirable, a 10-foot section is generally the most popular capacity for folding equipment. This folding equipment required to make these flashings and accessories could be a hand brake or more advanced equipment such as a press brake or an automated folder.

The flashing package will need to be made using the sheet metal flat stock at different widths. For a standard piece of drip edge, use an 8-inch strip of metal for the material stretch-out. Do this using a shear or a slitter to get the material shrunk down and ready to be folded into the specified trim piece. A slitter is a piece of equipment that pulls the sheet through and slices the sheet the length of the sheet. A shear is also a way to transform this into narrower pieces but utilizes a slashing motion. The 10-footlong, 24-inch-wide piece of flat stock is now in three 8-inch strips and will be the stretch out needed to fold into three pieces of drip edge. The rest of the coil stock material is then transformed into several accessory components for the metal roof.

After all the accessories are fabricated, the coil is now ready be fed into a rollforming machine. Whether it is shop formed or field formed, the rollforming machine pulls the remaining material from the de-coiler inside. Inside the machine there are several forming stations that gradually transform the flat piece of coil stock and make a continuous roofing panel to the length that the project requires.

Quality control is done throughout the rollforming process by the trained machine operator to ensure the panel meets the specification. With a cut-list in hand the entire project could be run in a factory setting, boxed, crated and shipped with the accessories for the project. However, if using portable equipment, the panels could be run on-site and coordinated at the same time instantaneous to installation. The job is ready to be installed and is ready in a fraction of the time than was 100 years ago.

This is a small, basic example of some of the fabrication methods used successfully by metal roofing fabricators and installers. While some may be more primitive and some may be more advanced, having the knowledge, right tools and equipment that were not available long ago makes metal roofing more accessible, efficient and more prominent than ever before in this industry.

James Hazen is national roofing sales manager at Englert Inc., Perth Amboy, N.J. To learn more, visit or call (732) 646-4915.

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